This invention relates to magnetrons. A magnetron produces a microwave output signal whose frequency is primarily dependent on the frequency characteristics of a resonant chamber associated with the magnetron. By altering the electrical properties of the chamber, the frequency of oscillation of the magnetron can be adjusted and this is often necessary to provide fine tuning of its output frequency. It is sometimes desirable to sweep the frequency of resonance periodically over a predetermined frequency range, but it is difficult to obtain fast sweep rates since the mechanical actuators and linkages usually necessary to produce an alteration of the electrical properties of the resonator exhibit a relatively great mechanical inertia.
It has been proposed to overcome these difficulties by using a tuning fork to vibrate one, or possibly both, of the end plates of the resonator chamber, and such an arrangement is described in our earlier UK patent application 7939909, now U.S. Pat. No. 4,311,968. The present invention seeks to provide an improved magnetron which is capable of superior operating performance.